Coiled load element

ABSTRACT

A load element consisting of a strip of material which is convoluted in cross section and which material is ductile and characterized in undergoing work hardening when stressed to beyond the elastic limit. The load element, due to the above mentioned characteristics, is characterized in deforming under substantially constant load once the resiliency thereof is overcome. The coiled load element can be in the form of a fractional part of a convolution or it can be in the form of multiple convolutions arranged either spirally or helically. The load element can be combined with a seal element and thereby form a combination which simultaneously seals between a pair of opposed members while exerting a substantially constant load therebetween.

United States Patent 1 Rode in] 3,794,311 [451 Feb. 26, 1974 1 COILED LOAD ELEMENT John E.- Rode, Fonda, NY.

[73] Ass'igneet- Temper Corporation, Fonda, N.Y. 221 Filed: May is, 1972 [21] Appl. No.: 253,302

[75] Inventor:

Primary ExaminerJames B. Marbert Attorney, Agent, or FirmMelvin A. Crosby [57] ABSTRACT A load element consisting of a strip of material which is convoluted in cross section and which material is ductile and characterized in undergoing work hardening when stressed to beyond the elastic limit. The load element, due to the above mentioned characteristics, is characterized in deforming under substantially constant load once the resiliency thereof is overcome. The coiled load element caribe in the form of a fractional part of a convolution or it can be in the form of multiple convolutipns arranged either spirally or helically. The load element can be combined with a seal element and thereby form a combination which simultaneously seals between a pair of opposed members while exerting a substantially constant load therebetween,

14 Claims, 14 Drawing Figures PATENTEDFEB26 m4 sum 2 or 2 FIG-7 COILED LOAD ELEMENT This invention relates to a load element, and is particularly concerned with a novel load element which is inexpensive to manufacture and which has a broad field of application.

There are many conditions arising as, for example, in connection with bearings, where it is desired for a certain preload to be imposed on and maintained on a work member. Such preloads can be obtained by extremely accurate machining arrangements, or by shimming, but such procedures involve considerable expense and time and also considerable variation is encountered from one installation to another.

Still further, when preloads are established by highly accurate machining, or by shimming and the like, it is difficult to establish uniform conditions over the entire part to be preloaded. For example, a bearing race, which is annular, can readily be preloaded to a higher degree on one side than the other when preloading is accomplished by the use of shims or the like. 7

The object of the present invention is the provision of a preload device in which the drawbacks and difficulties encountered previously in establishing preloads is eliminated and, instead, the establishing of a predetermined preload on a work member can be accomplished very reliably and at samll expense and without requiring that interfitting parts be machined to extremely close tolerances. I I

It is also an object of the present invention to provide a load element for use in establishing preloads which can readily be modified to provide for any predetermined load condition within a wide range of loads.

It is a further object to provide a load element of the nature above referred to which will fit within a specific space envelope.

A still further object is the provision of a spring member, usually having a high spring rate, which can readily be designed to fit within a predetermined space and to have a specific spring rate. I

Still a further object of this invention is the provision 'of a load element which can readily be combined with a sealing arrangement so that simultaneously with establishing acertain loadcondition a seal is also established. I

It is also an object of the present invention to provide a load element having an elastic recovery characteristic which remains unchanged throughout the range of compressibility of the load element.

A particular object of the present invention is the provision of a load element which, upon being placed under load conditions, establishes a predetermined load and maintains substantially the same load throughout a wide' dimensional variation in the parts with which the load element is assembled.

The foregoing objects as well as still other objects and advantages of the present invention will become more apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic perspective view showing a load element according to the present invention.

FIG. 2 is a transverse section indicated by line Il-ll on FIG. 1.

FIG. 3 is a view like FIG. 2 but shows a somewhat modified arrangement.

FIG. 4 is a sectional view like FIG. 2 but shows the load element combined with a seal element.

FIG. 5 schematically illustrates the combination of the load element with another type of seal element.

FIG. 6 is a graph showing the load deflection curve of a typical load element according to the present invention.

FIG. 7 is a vertical sectional view showing a load element according to the present invention formed by winding up a convoluted strip in the form of a spiral.

FIG. 8 is a fragmentary view showing a load element according to FIG. 7 encapsulated in rubber-like mate rial.

FIG. 9 is a fragmentary sectional view of a load element similar to FIG. 7 showing how the adjacent convolutions of the helical load element can be welded or otherwise secured together.

FIG. 10 is a fragmentary view of a helical load element with the convolutions facing in the opposite direction to those of FIG. 7. i

FIG. 11 is a view like FIG. 10 but shows a spiral or nested load element similar to what is shown in FIGS. 2 and 3 but with the convolutions reversed.

FIG. 12 is a fragmentary view showing a cross sectional configuration for the convolutions of the load element which will provide for a dual spring rate of the element upon'axial compression thereof.

FIG. 13 shows a load element according to the present invention having less than one complete turn.

FIG. 14 shows a load element according to the present invention in which the strip is formed into a noncircular configuration, specifically, rectangular.

BRIEF SUMMARY OF THE INVENTION:

According to the present invention, a strip of metal, preferably a metal which work hardens when stressed to beyond the elastic limit thereof, is formed so as to be convoluted in transverse cross section and is, furthermore, formed into a spiral.

Such an element, when placed between a pair of opposed members, such as a bearing race and a bearing cap, will deform in the axial direction when compressed with the deformation taking the form of an initial period of elastic deformation followed by a period of plastic deformation with the force required to collapse the load element during the period that plastic deformation occurs being substantially constant.

The element is formed of any metallic material exhibiting the characteristics of work hardening and among which materials are stainless steel and lnconel X. These materials are, furthermore, relatively resistant to corroson.

A load element of the nature referred to can have as many convolutions as desired, from a fraction of a convolution up to several convolutions, and it is, thus. quite simple to provide for a given preload merely by determining the length of the strip of metal which makes up the load element.

The invention also contemplates the combination of the load element with a seal element which may be in the form of a resilient member embracing, or surrounding, the outside of the load element and adapted for sealing between the opposed members engaged by the opposite ends-of the load element, the seal element being either metallic or nonmetallic in order to provide for the proper sealing effect and, at least in some circumstances, contributing to the load developed by the load element.

It is also contemplated to encapsulate the load element as within a block of rubber or rubber-like material.

It is also contemplated to wind the convoluted strip spirally in which case the convolutions thereof are in the same plane perpendicular to the axis of the element or to wind the strip helically in which case the individual convolutions of the element are in side by side relatron.

DETAILED DESCRIFTION OF THE INVENTION Referring to the drawings somewhat more in detail,

7 FIG. 1 shows a strip of metal 10 in the form of a spiral consisting of two complete convolutions. Strip 10 in axial cross section is convoluted as shown in FIG. 2 so as to have two end convolutions 12 concave toward the center of the ring and an intermediate convolution 14 concave toward the outside of the ring.

The strip 10 is formed as by rolling a flat piece of material between forming rollers and, in the natural course of events, such a strip will tend to assume a curved position. However, the strip, after being shaped by the forming rollers, can be shaped to any desired configuration, the circular configuration of FIG. 1 being only exemplary. For example, rectangular configurations are also contemplated having large fillets at the corners.

The extreme ends of strip 10 may be bent off so as wardly of and parallel to line 18. Two such lines are indicated at 21 and 23, each corresponding to a respective degree of plastic deformation of the load element.

Inasmuch as the load element is deformable in all circumferential portions thereof, it will be evident that misalignment of the parts to be loaded relatively by the load element will not interfere with the uniformity of the load unless the misalignment is most severe because the element will readily accommodate itself to such misalignment. Furthermore, minor irregularities in the surfaces engaging the element will present no difficulto be substantially flat as indicated at 16 in FIG. 2. The

adjacent convolutions do not nest together extremely closely but, inasmuch as the load element is provided for the purpose of developing axial loads, there is no need for the convolutions to be in direct face to face engagement.

When a load element of the type disclosed in FIG. 2

is interposed between two members and the members are moved toward each other, the load element will first deform elastically as shown by line 18 of the graph of FIG. 6, and will then deform plastically as shown by line 20 of the graph of FIG. 6.

I In FIG. 6, the force acting in the axial direction on the load element is the abscissa and is indicated by F, and the axial deformation of the element is the ordinate and is indicated bythe letter D.

When the load element commences to collapse, the maximum points of stress are located near the peaks of the curved portions 12 and 14, and it is in these portions of the load element that the elastic limit is first exceeded and which, therefore, work harden. When the peaks of the curves in the load element work harden, the load element becomes stiffer at that point and further yielding will occur immediately adjacent the hardened regions, so that these more greatly stressed regions will, in turn, work harden.

As the load element progressively collapses in the axial direction, work hardening will progress axially of the load element and the force required to collapse the load element will remain substantially constant, as

shown in FIG. 6, until the convolutions of the element commence to flatten out, whereupon the load will again rise sharply as indicated by line 22 of the graph of FIG. 6.

After plastic deformation of the load element commences, release of the load thereon will be accompanied by spring back of the element along a line rightties because the element will accommodate itself to such irregularities.

A particular advantage of'the load element according" to the present invention is that the load required to collapse the element stays at substantially the same level for a considerable amount of the axial distance that the element can be collapsed. Thus, with a given load element, wide machining tolerances in the parts which the element engages can be permitted and the load developed by the element will always be substantially the same.

In FIG. 3, the strip 24 is formed with rather shallow inwardly concave convolutions 26 and a rather shallow intermediate outwardly concave convolution 28. In the FIG. 3 modification, the convolutions of the load element nest somewhat more closely together than those of the FIG. 2 modification but, otherwise, the load ele ment operates in the same manner.

FIG. 4 shows the manner in which a convoluted spiral load element 30, according to the present invention, could be provided with a resilient outer seal member 32 embracing the outer circumference of the load element and extending over the ends thereof if desired. Member 32 is provided for establishing a seal between the parts engaged by the load element and may consist of any material suitable for the environmental conditions in which the load element is placed and the amount of pressure which it is required to be sealed.

Member 32 may be a resilient part formed separately from the load element and mounted thereon or it may be formed directly on the load element.

FIG. 5 shows a load element 34 according to the present invention with a convoluted metallic seal ring 36 in surrounding relation thereto. Seal ring 36'rnay be constructed similarly to the load element except that the strip of metal from which the seal ring is formed has the ends thereof in abutting relation, and fused or welded, so that the seal ring forms a continuous annulus surrounding the load element and which will engage the parts between which theload element is placed and form a seal about the load element.

The seal ring in FIG. 5, where it directly engages the parts which the load element engages, will contribute to the load developed by the load element and is taken into account when calculating the particular load element to be employed. Where the seal ring 36 engages only one of the aforementioned parts and engages another part which is not one of the parts engaged by the load element, then the seal ring is not taken into account when calculating the size of the load element.

In FIG. 7, a convoluted strip 38 is wound up to form a helix with the opposite ends 40 and 42 advantageously cut off so as to lie in parallel planes perpendicular to the axis of the load element. The same characteristics of deformation under substantially constant load obtain for the load element of FIG. 7 that obtain for those previously described and, likewise, the load element of FIG. 7 canbe combined with a coaxial seal ring if so desired. The load element of FIG. 7 preferably locates on the radially outwardly directed peaks of the convolutions thereof.

Flg. 8 shows how a spiral load element 44 according to the present invention could be encapsulated in a body-46 of rubber or rubber-like material and which material provides sealing regions at opposite ends of the load element for engagement with the parts between which the load element is disposed while simultaneously supporting the individual turns of the load element in proper alignment.

FIG. 9 shows how the individual turns 48 of a spiral I load element could be cemented, brazed or welded as at 50 either by a continuous helical treatment of the load element or by treating circumferentially spaced regions thereabout.

FIG. 10 shows a helical load element 52 similar to what is shown in FIG. 7 exceptwith the convolutions facing in the opposite direction so that the load element will locate on the radially inner side rather than on the radially outer side. The load element of FIG. 10 could be encapsulated the same as the modification of FIG. 8 and the individual turns c'ouldreadilybe welded together according to the procedure described in connection with FIG. 9.

FIG. 11 shows how a spiral load element 54 according to either of FIGS. 2 or 3 could be arranged with the convolutions reversed so that the load element of FIG.

11 would locate on the radially inner side rather than on the radially outer side as in the FIGS. 2 and 3 modifications. 7

FIG. 12 shows a configuration for the strip which provides for a dual spring rate. The specific configuration of FIG. 12 is disclosed more in detail in my copending application, Ser. No. 226,731, filed Feb. I6, 1972, and entitled Dual .Rate Spring and Load Element.

In any case, the strip 56 shown therein has end flanges 58 which elastically deform until' the axially outer sides of convolutions 60 are engaged by the parts between which the strip is confined, whereupon further elastic deformation will take place at a different rate until the elastic limit of the material of the strip is reached in the peaks of the convolutions, whereupon plastic deformation commences to occur. Upon releasing the axial loading on a load element in which the turns thereof are shaped as shown in FIG. 12, the spring back will occur at two different rates, reflecting the dual spring rate instead of at the single rate shown in FIG. 6.

FIG. 13 shows a load element 62 in which the convoluted strip making up the element is formed so as to have the ends 64 and 66 thereof in opposed relation.

FIG. 14 shows a load element 68 in which the strip making up the load element is formed to a rectangular shape with large fillets at the corners to prevent crimping of the strip. The modification of FIG. 14 could be either a spiral or a helical load element and could be combined with a coaxial load ring, and which load ring could be an endless member of substantially the same shape as the load element.

Modifications may be made within the scope of the appended claims.

What is claimed is:

1. In a load element adapted to be confine d between axially spaced parts and operable-to impose a predetermined load on the parts when compressed a predetermined axial amount, siad element undergoing a first period of resilient deformation under increasing axial force followed by a second period of plastic deformation under substantially constant axial force when compressed in the axial direction by movement of said parts toward each other, said load element comprising; a relatively thin elongated strip of resilient and ductile metal which work hardens when stressed beyond the elastic limit of the metal, said strip being undulating in axial cross section between the axial edges thereof and having the longitudinal ends free of one another, strip being formed in a plane perpendicular to an axis extending in the axial direction to bring said ends thereof into substantially one and the same axial plane.

2. A load element according to claim 1 in which said strip is formed in the plane perpendicular to an axis extending in the axial direction to make at least two convolutions.

3. A load element according to claim 1 in which the said strip in axial cross section comprises generally radial leg means projecting from opposite edges of said strip at the, axial ends of the undulations of said strip.

4. A load element according to claim 1 in which the said strip in axial cross section comprises a plurality of curved portions in end to end relation alternately concave in respectively opposite'direc'tions and forming the said undulations. i

5. A load elementaccording to claim 1 in which the said strip in axial cross section comprises a plurality of curved portions in end to end relation alternately concave in respectively opposite directions and forming the said undulations, and generallyv radial leg means at the axial edges of said strip extending from the. axially outer ends of the endmost ones of said curved portions.

6. A load element according to claim 1 which includes an endless annular seal member concentric with said element and in the same plane as said element and of substantially the same axial extend as said element.

'7. A load element according to claim 1 which includes a body of resilient material embracing said element on at least one radial side thereof and extending axially along said element and over at least the axially outer ends of said element.

8. A load element according to claim 2 in which the strips in axial cross section comprises individual curved portions in end to end relation forming said undulations, said curved portions being relatively shallow ancl each extending over a range of substantially less than degrees, said convolutions of said element being in radially overlapping relation and the said curved portions of radially adjacent convolutions of the element nesting together. I l 9. A load element according to claim 2 which includes an endless resilient seal member formedseparately from said element and disposed coaxially to said element, said seal member being of about the same axial length as said element and having opposite end regions adapted for sealing engagement with the parts which are disposed at the opposite ends of said element and which develop compressive forces thereon.

10. A load element according to claim 1 in which said element is substantially stress free in initial noncompressed condition. I

convolutions of the load element in axially adjacent relation, each convolution in cross section comprising substantially radial legs at the opposite axial edges and at least one curved portion extending between said legs and connected to one and the same radial end of each thereof, and means connecting the free ends of the legs of axially adjacent convolutions together.

14. A load element accordingto claim 13 in which said means comprises metal fusion means interconnecting the free ends of said radial legs. 

1. In a load element adapted to be confined between axially spaced parts and operable to impose a predetermined load on the parts when compressed a predetermined axial amount, siad element undergoing a first period of resilient deformation under increasing axial force followed by a second period of plastic deformation under substantially constant axial force when compressed in the axial direction by movement of said parts toward each other, said load element comprising; a relatively thin elongated strip of resilient and ductile metal which work hardens when stressed beyond the elastic limit of the metal, said strip being undulating in axial cross section between the axial edges thereof and having the longitudinal ends free of one another, strip being formed in a plane perpendicular to an axis extending in the axial direction to bring said ends thereof into substantially one and the same axial plane.
 2. A load element according to claim 1 in which said strip is formed in the plane perpendicular to an axis extending in the axial direction to make at least two convolutions.
 3. A load element according to claim 1 in which the said strip in axial cross section comprises generally radial leg means projecting from opposite edges of said strip at the axial ends of the undulations of said strip.
 4. A load element according to claim 1 in which the said strip in axial cross section comprises a plurality of curved portions in end to end relation alternately concave in respectively opposite directions and forming the said undulations.
 5. A load element according to claim 1 in which the said strip in axial cross section comprises a plurality of curved portions in end to end relation alternately concave in respectively opposite directions and forming the said undulations, and generally radial leg means at the axial edges of said strip extending from the axially outer ends of the endmost ones of said curved portions.
 6. A load element according to claim 1 which includes an endless annular seal member concentric with said element and in the same plane as said element and of substantially the same axial extend as said element.
 7. A load element according to claim 1 which includes a body of resilient material embracing said element on at least one radial side thereof and extending axially along said element and over at least the axially outer ends of said element.
 8. A load element according to claim 2 in which the strips in axial cross section Comprises individual curved portions in end to end relation forming said undulations, said curved portions being relatively shallow and each extending over a range of substantially less than 180 degrees, said convolutions of said element being in radially overlapping relation and the said curved portions of radially adjacent convolutions of the element nesting together.
 9. A load element according to claim 2 which includes an endless resilient seal member formed separately from said element and disposed coaxially to said element, said seal member being of about the same axial length as said element and having opposite end regions adapted for sealing engagement with the parts which are disposed at the opposite ends of said element and which develop compressive forces thereon.
 10. A load element according to claim 1 in which said element is substantially stress free in initial noncompressed condition.
 11. A load element according to claim 1 in which said strip is formed to a helical configuration with adjacent convolutions of the load element in axially adjacent relation.
 12. A load element according to claim 1 in which said strip is formed to a helical configuration with adjacent convolutions of the load element in axially adjacent relation, and an annular body of resilient material encapsulating said load element.
 13. A load element according to claim 1 in which said strip is formed to a helical configuration with adjacent convolutions of the load element in axially adjacent relation, each convolution in cross section comprising substantially radial legs at the opposite axial edges and at least one curved portion extending between said legs and connected to one and the same radial end of each thereof, and means connecting the free ends of the legs of axially adjacent convolutions together.
 14. A load element according to claim 13 in which said means comprises metal fusion means interconnecting the free ends of said radial legs. 